Counter/Timer Features; C/T Channels; C/T Clock Sources - Data Translation DT9812 Series User Manual

Counter/Timer Features

This section describes the following features of counter/timer (C/T) operations:
• C/T channels, described below
• C/T clock sources, described on
• Gate types, described on
• Pulse types and duty cycles, described on
• C/T operation modes, described on

C/T Channels

The modules provide one 32-bit counter/timer (16 bits in rate generation mode). The counter
accepts a C/T clock input signal (pulse input signal) and gate input signal, and outputs a
pulse signal (clock output signal), as shown in
C/T Clock Input SIgnal
(internal or external)

C/T Clock Sources

The following clock sources are available for the counter/timers:
• Internal clock – Through software, specify the clock source as internal, and specify the
frequency at which to pace the counter/timer operation. The frequency of the internal
C/T clock can range from 15 Hz to 12 MHz.
• External clock – An external clock is useful when you want to pace counter/timer
operations at rates not available with the internal clock or if you want to pace at uneven
intervals.
Connect an external clock with a maximum recommended frequency of 6 MHz to the
Counter 0 In signal on the module. Using software, specify the C/T clock source as
external, and specify a clock divider between 2 and 65536 to determine the actual
frequency at which to pace the counter/timer operation. For example, if you connect a
6 MHz external C/T clock and use a clock divider of 2, the resulting C/T output
frequency is 3 MHz. Counter/timer operations start on the falling edge of the Counter 0 In
signal.
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Counter
Gate Input Signal
(software or external
input)
Figure 21: Counter/Timer Channel
Figure 21.
Pulse Output Signal
Principles of Operation
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